Teletypewriter exchange system



June Z9, 1937. c. v.co1 l.|Ns 2,085,637

TELETYPEWRITR EXCHANGE SYSTEM Filed NOV. 14, 1956 y 4 Sheets-Sheet l` w d?. m. .Si v l MGP* /Nl/EN TOR 8V C. VCOLL/NS A TTOR/VE Y rune. mw Hlm uso.;

-lune 29, 1937.

' c. V. COLLINS TELETYPEWRITER EXCHANGE SYSTEM Filed Nov. 14, 1936 4 Sheets-Sheerl 2 /N VENTOR C. IKCOLL/NS VCV Sv June 29, 1937. c. v; coLLlNs TELETYPEWRITER EXCHANGE SYSTEM yF'i-led NOV. 14, 1956 4 Sheets-Sheet 5 m. .gl

@Mums ATTORNEY June29, .1937. c. v. coLLrNs 2,085,637

` TELETYPEWRITR EXCHANGE SYSTEM Filed Nov.' 14,'1936 4 sheets-sheet 4,

cAu.

ATTORNEY Patented .une 29, 1937n UNITED STATES PATENT oF'FieE TELETYPEWRITER EXCHANGE SYSTEM Application November 14, i936, Serial No. 110,922

4 Claims.

This invention relates to telegraph systems and `more particularly to a sys'tem arranged to operate in conjunction with a telephone exchange office located at a distant point from the teletypewriter1 exchange oice, for `establishing communication connections with teletypewriter subscribers stations.

An object lof the invention is to furnish teletypewriter exchange service to a town having a small number of Vteletypewriter subscribers stations to which connections are established through a local central olice telephone switchboard.

According to the present invention a system is l5 provided for furnishing teletypewriter service to` more than one subscriber at an outlying point, over a lesser number of telegraph lines, or channels, extending from a teletypewriter switchboard. The connections between the teletypewriter subscribers .stations and the teletypewriter switchboard are established by an operator at the telephone central oiiice switchboard located nearest to the outlying point. When a call is originated i by a subscriber at an outlying teletypewriter station a lamp associated with the sublscribers lineand located at an operators position in the telephone oifice switchboard, lights. If the associated telegraph line or lines to the tele-typewriter switchboard are not busy, the operator dials the number of the calling teletypewriter,subscribers station. The number consists of one or more digits and is shown on a plate associated with the lighted lamp. Dialing the last digit of the number connects the calling subscribers line to a telegraph CIG ' channel and a lamp located at the teletypewriter switchboard, lights, indicating the number of the teletypewriter subscribers at the outlying point that desires service. Upon receiving the lineI lamp signal at the teletypewriter switchboard the teletypewriter operator connects her teletypewriter to the telegraph line, using her cord circuit, and proceeds to transmit a code informing the subscriber thathe is prepared to receive the number of the called teletypewriter subscrib- 1" ers station or the message. Disconnection is effected by the calling subscriber operating a calldisconnect key, momentarily opening the line circuit., thereby causing the operation of a supervisory lamp at the operators position in the teletypewriterl switchboard. The operation of the supervisory lamp is a signal for the teletypewriter operator to cut in on the line with customary challenge and if there is no response, to operate the stop key and then disconnect. The operated 5.5 equipment at the telephone central office and.

the teletypewriter exchange is then automatically restored to normal.

A preferred embodiment of the invention will now be described in more detail with reference to the accompanying drawings in which like parts in similar circuit arrangements are identified `by corresponding reference numerals in the 400 and the 500 series, respectively.

Referring to the drawings:

Figure 1 shows a diagrammatic layout or" the complete system wherein three teletypewriter subscriber stations are connected to an outlying manually operated telephone central office. Facilities are provided at the switchboard in the telephone central oice for connecting any one of the three teletypewriter subscriber stations to an associated channel line extending to a teletypewriter exchange. At the teletypewriter exchange are provided for interconnecting by means of any one of a plurality of cord circuits, the associated channel and any one of a plurality of teletypewriter subscriber stations associated with all other teletypewriter exchanges. Also calls originating in any one of the teletypewriter subscriber stations connected with a teletypewriter exchange may be established through the associated teletypewriter exchange, over an associated channel line and through the telephone central oce to any one of the teletypewriter subscriber stations connected to a distant telephone central office.

Fig. 2 is a relative arrangement of Figs. 3 to 6; Fig. 3 represents three teletypewriter subscriber stations to which are respectively assigned code numbers 530, 540J and 560. `The station having code number 530 is shown in detail and the stations having code numbers 540 and 560, re-

spectively, are shown in diagrammatic form;

Fig. 4 shows three line circuits respectively extending from the teletypewriter subscriber stations of Fig. 3 and terminatingin a selector circuit at the telephone central oilice whereat a telephone operator may upon receipt of a calling signal connect the calling line circuit to an associated channel extending to the distant teletypewriter exchange whereat a selector circuit similar to that at the telephone central office, is also operated, the operation of both selector circuits being simultaneous;

Fig. 5 shows a channel terminating at the distant teletypewriter exchange whereat the selector circuit extends it automatically to any one of the associated spring jacks in a manually operated switchboard. By means of a teletypewriter operators cord circuit, the connection continued through the selector circuit is extended to the called teletypewriter subscriber station; and

Fig. 6 shows a teletypewriter operators cord circuit, a calling spring jack and a teletypewriter subscriber station for connection thereto through selector circuit shown in Figs. 4 and 5, to the called teletypewr er subscribers station.

Referring to Fig. 3 whereat three teletypewriter subscriber stations 30| 302, 303 are shown as representing those having code numbers 530, 540, and 560, respectively, the three stations are shown respectively connected by line circuits 304, 305, and 35E extending tothe selector circuit at the telephone central office. The selector circuit is similar to thatY disclosed in United States Patent 1,946,216 granted to F. S. Kinkead, October 6, 1934, except for a few minor changes required to adapt it to the system described herein. A selector circuit is common to the three line circuits except for the line relays 40|, 402, and 403 and the subscribers busy relays 404, 405, and 405, the relays oi both groups being respectively individual tothe line circuits 304, 305, and 306. Relays 404, 405, and 406 correspond to relays P in the Kinkead patent, supra, wherein only a single P relay is required.

For the purpose of describing the invention it is assumed herein that a call is initiated at station 30| to a subscribers station connected to a distant teletypewriter exchange shown in Figs. 5 and 6 of the drawings, the called subscribers station being station 0|5. The line circuit 304 is normally close-d Vand relays 301 and 40| of Figs. 3 and 4 are normally operated. The subscribers station 30| in initiating the call momentarily operates start key 308 and then operates the call-disconnect key 3| by turning the handle in a clockwise direction as far as possible and then releasing it whereby the line circuit 304 is opened for a period of ve seconds to allow the release of relay 40| at the telephone vcentral office. Relay 301 is energized during the open interval of the line, as will be hereinafter described. By means of the make-before-break contact operated by the time key 3| the teletypewriter set at station 30| is maintained in a closed circuit during the open interval caused by key 3| The release of relay 40|, Fig. 4, at the telephone central oice releases at its armature and contact signal relay 401. Signal relay 401 releases to thereby light lamp 408 at the telephone switchboard at the central office. Signal relay 401 in operating shunts relay V40| so that the latter relay remains released when the calldisconnect key 3|| again closes the line circuit after the five-second interval. Relay 40| through its lowermost winding is now energized by an obvious auxiliary circuit extending over its `armature and back contact to battery to thereby hold the relay in a released position. The line circuit is now closed through to the telephone central oliice through resistance 4|0, back contact and inner lower armature of relay 401, innermost lower armature and back contact of relay 404 to battery.

Normally all relays of the selector circuits shown to the right of the line relays 40|, 402, 403 of Fig. 4 and to the left of line relays 50|, 502, 503 of Fig. 5, except relays 4| 2 and 5|2, are in their release-d position. Relays 50,2, and 503 are normally in their operated position.

l The operator at the outlying' telephone central oiiice upon observing the lighted lamp 408, which has a number plate associated therewith bearing the numeral 530, the code number of calling station 30|, operates dial key 439 which is of the non-locking type, and proceeds to operate dial 409 to send the three digits of the code number 530 of station 30|. However, should the associated channel circuits extending through the teletypewriter exchange be busy, one of the busy relays 404, 405, and 405 would be operated and therefore busy lamp 442 at the telephone central oice and the supervisory lamp, such as lamp 3|2 at each of the subscribers stations 30|, 302, and 303 would be lighted indicating that the calling subscriber at station 30| must wait for an idle condition of a channel circuit. Guard lamp 4|3 may also be lighted if the associated channel circuit 4| is busy, and selector switch S1 is at the time in an off-normal position.

In response to the transmission of the five pulses representing the rst digit of the code number of the calling station, relays 4|2 and 5|2 follow the pulses and respectively apply ground intermittently tothe rotary magnets 4|3 and 5|3. These magnets operate comparatively simultaneously taking into consideration the delay factor, or lag, necessitated by transmission through the signal repeaters 4| 4 and 5|4. Repea ers 4|4 and 5| 4 may be of any suitable type well known in the art, such as those disclosed in United States Patent 1,479,430 granted to J. M. Fell on January 1, 1924. The operating circuit for the relays 4|2 and 5|2 may be traced from ground 438, make-before-break contact of relay 441, conductors 464 and 440, normally closed contact of stop key 44|, conductor 444, dial 400, (dial key 430 is held operated while dialing) conductor 443, cuter upper armature and contact of relay 446 and upper armature and contact of relay 422 in parallel, through the upper winding of relay 4|2, telegraph repeater 4|4, associated channel line 4| telegraph repeater 5|4, through the upper winding of relay 5|2, contact and upper armature of relay 522, contact and outer upper armature of relay 546 in parallel, conductor 543, contact of dial key 539, conductor 544, normally closed contacts of stop key 54|, conductors 540 and 564, make-before-break contact of relay 541 to grounded negative battery 538.

The operation of the selector circuit shown in Fig. 4 will be described first. The ground applied over the left contact and armature of relay 4|2 during each open period of the line circuit 304 is extended over parallel paths, one through the winding of rotary magnet 4|3 to grounded negative battery and the other over the back contact and inner lower armature of relay 446, through the winding of relay 4|1 to grounded battery. The wipers lili and 4|5 of the selector switch S1 will be stepped up one contact, or terminal, for each pulse of relay 4|2, but relay 4|1 which is of the slow-release type will remain operated for the duration of the live pulses. The off-normal spring 418 will transfer ground from its lower to its upper contact on the first step of the selector switch S1. Relay 4| 1 in operating closes a circuit extending from ground on the upper contact of ori-normal spring 4|8, conductor 420, normally closed contact of relay M5, armature and front contact of relay 4|1, conductor 42|, through the windu ing of relay 422, to grounded battery. thereby operating relay 422. Relay 422 also is of the slow-release type and remains operated for the duration of the ve pulses. After the last, or fth, pulserelay 4 1 will release and apply ground to a circuit extending from conductor 420, normally closed contact of relay 4|9, armature and back contact of relay 411, outer lower armature and front contact of relay 422, conductor 423,

A, back contact and outer lower armature of relay 424, wiper 415, resting on the fth terminal of bank No. 1 through the winding of relay 425,

425 operates and locks to ground over its upper l armature and contact. When stepper switch S1 is operated, ground conductor 423 is connected to guard lamp 413 indicating toy the operator that `the switch is functioning and it is in olif-normal position.

After the last, or fifth, pulse slow-release, or non-pulsing, relay 411 releases and ground is thereby removed from the winding of slow-release relay 422 which, in turn, releases a. short time later. Relay 422, in releasing, transfers ground from the circuit including conductor 423,

i toa circuit including conductor 423, contact and outer lower armature of relay 446, through the winding of release magnet 429, to grounded bah l tery. Release magnet 429 operates and wipers 418 to return to normal.

normal spring 418,wi1l again operate as herein- `before described. Relay 441 will release after the dial 443 returns to its normal position. The release of relay 411 closes a circuit traceable from ground at the armature and upper Contact of olf-normal spring M8, normally closed contacts of relay 4&9, armature and back contact of re lay 411, outer lower armature and front contact of relay 422, conductor 423, back contact and outer lower armature of relay 424, wiper 415, in engagement with its third terminal, outermost lower armature and Contact of relay 425, through the winding of relay 444, conductor 433., Contact and inner lower armature of relay 436, to grounded battery. Relay 4134 which is individual to subscribers station 331 operates and thenlocks to ground at its inner upper armature and contact. Relay 434, in operating, causes at its outermost lower armature and contact an obvious operating circuit for lighting busy lamp 442. After the release of relay 411, relay 422 releases and thereby closes a circuit for operating release magnet 429 as hereinbefore described. Magnet 429 operates and thereby causes the wipers of the selector stepping switch S1 and the movable member of vertical ofl-normal spring The guard lamp 413 is now extinguished. Relay 444 in operating disconnects grounded battery at its back contact and inner lower armature from the line circuit of station 331 and substitutes: the grounded battery at the upper armature and back contact of relay 441, in parallel with the operating circuit for relay 444 in the path extending through i the uppermost winding of relay 4111 to grounded battery. Relay 441 in response to the current in its uppermost winding reoperates thereby causing the reoperation of signal relay 4131. Relay 4111 in reoperating opens the shunt path around the middle winding of relay 441 and extinguishes lamp 443 because the operator has now only to dial the third digit which is the last digit of the code number of all teletypewriter subscriber stations connected to the distant telephone central oice.

Similarly, when the third digit 0 of the code number 530 of the calling subscribers station No. 301 is dialed, the wipers 415 and 4i@ will step up to their respective tenth terminals on banks Nos. 1 and 2 and guard lamp 413 again lights. As stated hereinbefore, the response of relay 412 to the dialing pulses in addition to operating the rotary magnet, operates relay 411 which remains operated during the pulsing. The operation of relay 411 operates relay 422. After pulsing is completed, relay 411 releases and closes a circuit extending from ground on the operated Vertical olf-normal spring 4118, normally closed contact of relay 419, armature and back contact of relay 411, outerlower armature and front contact of relay 422, conductor 423, back contact and outer lower armature of relay 424, wiper 415 on its tenth terminal, conductors 431 and 432, through the winding of relay 424, conductor 433, front Contact and inner lower armature of relay 422 to grounded battery. A parallel path is closed from connection 434 on conductor 433 to connector 436 also on conductor 433, to the contact and outer lower armature of relay 43B, to grounded battery. Anotherparallel path is closed from connection 436 through theV winding of relay 441, conductors 432 and 43E, to v the tenth terminal on bank No. 1 engaged by the grounded wiper 415. Relays 424 and 441 operate. Slow release relay 422 releases. Relay 424 in operating closes a circuit to ground at its inner lower armature and associated contacts thereby short-circuiting the operating circuit for busy Vlamp 442 which circuit extends to ground at the contact and outer lower armature of relay 404 and the busy lamp 442 is maintained lighted independently of relay 4114. Relay 424, in operating, also closes at its upper make-before-loreak contact, a circuit extending to ground at the nor mally closed contacts of relay 431. The grounded conductor 423 at the back contact of the outer lower armature of relay 424 is at this time transferred at the outer lower make-beforebreak contact of relay 424, from the Wiper 415 to the wiper 414 which is in engagement with the tenth terminal on bank No. 2 to hold relays 424 and 441 operated. When relay 441 operated, it effected at its outer lower armature and back contact the release of relay 425, and removed ground at its make-before-break contact from the normally energized associated channel line 411 and substituted the subscribers line circuit. Relay 441, in operating also short-circuited dial 409 at its outermost lower armature and contact. Relay 441, in operating, performs other functions such as closing acircuit from grounded battery at its inner lower armature and front contact, extending over conductors 448 and 449, through the winding of slow-release relay 451! and the lower winding of relay 431 in parallel, conductor 45l, right contact and armature of relay 412 after the tenth pulse, to ground. Relays 450 and 431 operate. Relay 431 in operating locks through its upper winding to ground at the `armature and front contact of relay 454 and Vdisconnects ground from conductor 426 and the winding of rotary magnet 413.

The operation of the selector switch shown in Fig. will now be described. As hereinbefore stated, relay 512 follows the three sets of pulses 5-3--10 transmitted by dial 409. In response to the iirst pulse of the set of five, the grounded armature of relay 512 moves to its right-hand contact and closes two parallelpaths, one eX- tending over a conductor connected to the outer upper armature and back contact of relay 524, through the windingrof rotary magnet 513 to grounded battery, and the other over the back contact and inner lower armature of relay 546 to the winding of slow-to-release relay 511 to grounded battery. Rotary magnet 513 operates five times to set wipers 515 and 516 of selector switch S2 to their respectively associated Iifth terminals on banks Nos. I and 2. Relay 511 being slow to release, remains operated for the duration of the iive pulses repeated by relay 512. In response to the first operation of S2 the vertical off-normal spring 518 transfers ground from its lower toits upper contact and thereby closes two parallel paths, one extending over the normal contacts of relay 519, armature and front contactof slow-to-release relay 511, through the Winding of relay 522 to grounded battery, and the other to grounded battery at guard lamp 513. Guard lamp 513 lights indicating that selector switch S2 is in an oir-normal position. Relay 522 being slow to release, operates and remains operated for a short interval after relay 511 releases. When relay 511 releases at a` time when wiper 515 is on its fifth terminal, a circuit is closed from the ground on vertical off-normal spring 518 over its upper contact, normal contacts of relay 519, armature and back contact of relay 511, outer lower armature and front contact of relay 522, conductor 523, back contact and I lower armature of relay 546, through the winding of release magnet 523 to grounded battery. Release magnet 529 operates and restores the wipers 515 and 516 of selector switch S2 to normal and consequently the vertical off-normal spring 518 is restored to normal, that is, tothe lower contact to causev the deenergization of release magnet 529.

Similarly, when the second digit 3 of the calling code number 530' is dialed wipers 515 and 516 will step up to their respective third terminals on banks Nos. I and 2 and guard lamp 513 will again light. Relays 511 and 522 and vertical offnormal spring 528 will again operate as hereinbefore described. Relay 511 will release after dial 409 returns to its normal position. 'I'he release of relay 511 causes a circuit traceable from ground at the armature and upper contact of vertical off-normal spring 4518, normally closed contacts of relay 519, armature and back contact of relay 511, outer lower armature and front contact of relay 522, conductor 523, back contact 542 and at its innermost upper armature and contact a locking circuit for itself to ground. Relay 504 in operating also disconnects at its innermost lower armature grounded negative battery from the tip conductor of jack 512 and substitutes therefor the grounded negative battery at the make-before-break contact of relay 541. At its outermost upper armature and contact it connects grounded battery to a conditioning circuit for line lamp 558 which will be lighted after the third digit of the calling code number is dialed, as will be hereinafter described. After release of relay 511, relay 522 releases and thereby closes a circuit for operating release magnet 52S as hereinbefore described. Magnet 529 operates and thereby causes the wipers 515 and 516 of stepper switch S2 and the movable member of vertical olf-normal spring 518 to return to normal. The guard lamp 513 is again extinguished.

Similarly, when the third digit 0 of the calling code number 530 is dialed, the wipers 515 and 516 will step up to their respective tenth terminals on banks Nos. 1 and 2 and guard lamp 513 again lights. As hereinbefore stated, the response of relay 512 to the dialing pulses in addition to operating the rotary magnet 513, operates relay 511 which remains operated during the pulsing. The operating of relay 511 operates relay 522. After pulsing is completed, relay 511 releases and closes a circuit extending from ground at the operated vertical off-normal spring 518, normal contact of relay 519, armature and back contact of relay 511, outer lower armature and front contact -of relay 522, conductor 523, back contact and outer lower armature of relay 524, wiper 515 on its tenth terminal, conductors 531 and 532, through the winding of relay 524, conductor 533, front contact and inner lower armature of relay 522 to grounded battery. A parallel path is closed from connection 534 on conductor 533 to connection 536 also on conductor 533, through the contacts and outer lower armature of relay 530, to grounded battery. Another parallel path is closed from connection 536 through the winding of relay 541, conductors 532 and 531 to the tenth terminal on bank No. 1 engaged by grounded wiper 515. Relays 524 and 541 operate and are locked through the front contacts and inner lower armature of relay 524. Relay 524, in operating, closes a circuit from ground at its inner lower armature and contact and thereby short-circuits the path extending to ground at the contacts and outer lower armature of relay 504, and busy lamp 542 remains lighted. Relay 524, in operating, also closes at its upper make-before-break contact a circuit extending to ground at the normal contacts of relay 531 to hold rotary magnet 513 operated. The'grounded outer lower armature in engagement with the front contact of relay 522 will be transferred at the outer lower make-before-break contact of relay 524 from wiper 515 to wiper 516 which is in engagement with the tenth terminal of bank No. 2 to hold relays 524 and 541 operated. When relay 541 operated it removed grounded negative battery 538 at its make-before-break contact from the channel line 411 in a normally energized condition, and connected the channel line 41 1 to the tip conductor of spring jack 512 which at this time is connected to grounded positive battery 511. Relay 541, in operating, closes a circuit extending from grounded positive battery, tip of jack 512, through the winding of relay 501, innermost'lower armature and front contact of busy relay 504, upper armature and front contact of relay 541, conductors 564 and 540, normally closed contact of stop key 54|, conductors 565 and 565, outermost lower armature and front contact of relay 541, conductor 543, outer upper armature and contact of relay 546, and upper ar- `4|2, contact and upper armature of relay 422 andv contact and outer upper armature of relay 446 in parallel, Conductory 443, front contact and outermost lower armature of relay 441, conductors 446 and 465, normally closed contact of stop key 45|, conductors 440 and 464, front Contact and upper armature of relay 441, front contact and innermost lower armature of relay 404, through the middle winding of relay 40| subscribers line 364, break contact of key 3H, through the winding of relay 361 and printer magnet 3| 3, sending contact 3|4, start key 308, to ground. The reversal of current through relay 301 which was effected when grounded positive battery connected over the normally closed contact of the tip spring of jack 512 was connected over the tip conductor, through the innermost lower armature and front Contact of relay 504 and upper armature` and front contact of relay 541, was connected to conductor 540, operates relay 301 to thereby close and lock `the motor control circuit as well understood. Motor 3|0 operates. Relay 541, in operating, short-circuited dial 509 as will be seenby tracing the circuit just described.

At the time when wiper 5|6 engages the tenthV terminal on bank No. `2 a parallel path is closed extending from grounded wiper 516, conductors 561 and 549, over three other parallel paths respectively extendingthrough the windings of relays 552, 553, and 554, contacts andupper armatures of relays 555, 556, and 551 to grounded battery. Relays 552, 553, and 554 operate and close locking circuits for themselves extending over their lower armatures and contacts to ground.

v Relay 552 in operating completes a crcuitprepared by relay- 504` and thereby lights line lampV The teletypewriter exchange operator upon 550. seein-g lamp 550 light, inserts the answering plug 606 of the associated cord circuit into jack 512. The sleeve relays 602 and 555 operate in an obvious circuit. Relay 555, in operating, opens at its upper armature and contact the locking circuit for relay 552 which releases to cause lamp 558 to be extinguished, and at its lower armature and contact closes a circuit extendingV from .grounded battery at the lower armature and contact of relay504, conductor 559, lower 'armature and contactof relay 555, conductor 563,

through three parallel paths respectively extending through lamps 560, 56|, 562 to ground. Lamps 560, 56|, and 562 light indicating that single channel line 4|| is busy. Relay 602, in

p operating,y closes at its inner` lower armature `closed contacts, in series, of typing key 606,

and Contact a circuit extending from grounded battery, conductor 603, through the winding of` relay 604 to ground. Relay604 operates. Relay 602, in operating, also `closes at its `upper armature and front contact the communication circuit extending from ground on the line circuit of subscribers station `30| as hereinbefore traced, over the lowermostand uppermost normally through the upper winding of repeater relay 605,

armature `and right contact of repeater relay 601 to grounded negative battery. The extension `oi the communication circuit to grounded negative battery at the right contact of repeater relay 601 reverses the polarity of the current that was previously impressed on the line by grounded positively battery connected to the tip spring of jack 512, the latter battery being removed from the `line when plug 60| was inserted into jack 512. The grounded negative battery normally connected to the right contact and armature of repeater relay 601 is also connected through the lower winding of repeater relay 605 to the contact and inner left armature of relay 604 to ground.` Relay 604 in operating closes at its inner right armature and contact a circuit extending from ground through the lower winding of repeater relay 601 to the armature and left contact or repeater relay 605 to grounded negative battery and its outer right armature and contact a circuit extending from grounded negative Ybattery through themake-befcre-break contact of sleeve relay 62| through the upper winding of repeater relay 661 to armature and left contact o repeater relay 665 to grounded negative battery. The operation of. relay 604 therefore places the repeater relays 605 and 601 in condition for operation.

The operator then operates typing key 606 which, in operating, connects the operators teletypewriter set comprising transmitting contact 6| 0 and printer magnet 6H to the cord circuit shown in detail in Fig. 6. Other typing keys such as keys 608 and 609 are shown and may be employed for lconnectingother cord circuits,

not shown, to the operators teletypewriter. The

operator now challenges the subscriberat station 30| by transmitting signals corresponding to OPR to which the subscriber replies by transmitting signals corresponding to the code number of the desired subscribers station. The operatorupon receiving the signals corresponding to the code number of the desired subscribers station inserts the calling plug 6| 2 into a jack which is connected to the line circuit of the desired subscriber. In some cases it may be desired to have theA line circuit of a calling jack connectedthrough another selectorv circuit such as either of those shown in Figs. 4 and 5, or some other kind of a circuit that may be adapted for use with an individual subscribers station or a group of subscribers stations. Rectangles 6|4 and 615 respectively represent in diagrammatic form a selector circuit and a subscribers station connected to the teletypewriter exchange by means of jack 6|3.

The operators circuit shown in the lower part of Fig. 6 provides, as stated hereinbefore, for lassociating the `operators teletypewriter with an associated cord circuit by means of a typing key such as606, 608, and 600. Provision is also made for preventing the teletypewriter running idle, that is, the printer motor is running when no punched tape is prepared `for transmitting 'signals. Relay 6|6 is connected in series with the a period of ve seconds.

yinterval causes the pulsing relays 4|2 and 5|2 Yto operate to their off-normal position, deenernect key, provides for opening the transmission circuit of the operators set approximately ten seconds to transmit a ten-second? disconnect signal. Key 6|9 identied as the toll recall key provides for opening the transmission circuit Vfor approximatelyseven seconds to transmit a recall signal.

nected, both keys should not be operated at the.

As these keys are serially consame time. Y

Y Disconnecton When communication is completed and it is desired to clear the selection preparatory to the next call the disconnect signal is preferably sent from the station of the calling subscriber. The calling subscriber operates the call-disconnect key-3H which opens the channel line 4|| for The prolonged open gizes the middle Winding `of slow-release relay 40| which relay does not release because its uppermost Winding is energized and releases the slow-release relay 50| to close a circuit at its lower armature and contact from ground, ring Yconductors of jack 512 and plug 50|, over twoV parallel paths, one through the disconnect lamp 620 and the other through the Winding of relay 622, conductor 623, contadt and outer lower armature of relay E02 to grounded battery. Disconnect Vlamp 620 lights and relay v622` operates to close a locking circuit for itself over its armature and contact to ground. Also, the operation of pulsing relays 4|2 and 5|2 through their offnormal positionsV causes the selector switches Si and Sz to operate to their first contacts, respectively. The operation of the switches Si and S2 causes the guard lamps 4|3 and 5|3 to operate. Ther operator at the telephone exchange ignores any momentary lighting of the guard lamp 4|3, but the operator at the teletypewriter exchange, upon observing the lighted lamps 620 and 5|3, reoperates typing key 606 to again connect her teletypewriter to the engaged cord circuit and acknowledges the disconnect and guard signals with the customary challenge-of OPR and the calling subscriber at station 30| advises CLR meaning clear. The teletypewriter operator then sends a stop signal H which automatically opensmotor control contact 3|5 in the well known manner and stops the-calling subscribers teletypewriter motor. The transmission of the H signal from transmitting contact 6|() also stops the operation of the, printer motors at the teletypewriter exchange and station 6|5.

' The teletypewriter exchange operator then operates the stop key 54|. The operation of the stop key 54| initiates the restoration of the operators Yequipment in both Figs. 5 and 4 simultaneously. The equipment in Fig. 5 will be described first; The off-normal spring 5|8 in normal position Vconnects ground at its lower contact through the left-hand operated contact of stop key 54|,

ythrough the winding ofV relay 568, conductors 569 Y,at the inner lower armature and contact of relay 541. Relay 546 Yoperates and closes at its inner upper armature and contact a locking circuit to ground, opens the operating circuit for release magnet 529, opens a short circuit across the upper armature and contact of relay 522, which relay will later open the line, or communication circuit, and transfers the operating circuit for relays 5|1 and 5|9 from the righthand contact of relay 5|2 to the armature and front contact of relay 531 to ground. Inasmuch as relay 531 is operated at this time, relays 5|1 and 5|9 operate. Stop key 54| on being operated causes the communication circuit to be opened at the normally closedV middle contact and therefore relay 5|2 releases to its righthand position to thereby cause the release of relays 531 and 550. Also, stop key 54| upon being operated closes at its outermost right-hand contact a circuit extending from ground at the inner lower armature and associated contact of relay 524, conductors 513 and 514, outermost right-hand contact of stop key 54|, conductor 515, front contact and armature of relay 5| 9, conductor 516, through the winding of relay 522 to grounded battery. Relay 522 operates to open at its upper armature and contact the communication circuit. If stop key 54| is operated for a short period only, the slow-release action of relay 522 maintains the open condition in the communication line circuit for a sufficient time after the release of stop key 54| to assure the complete release of relay 531 and the operation of rotary magnet 523. Selector switch Sz operates one step. At this time, that is, after stop key 54| is released, off-normal spring 5I3 in its-operated position connects Vground to a circuit extending over front contact and armaturev of relay 5| 9, conductor 516 through the winding of relay 522 to grounded battery. Relay 522 which released when stop key 54| was released, will reenergize as long as relays 5|1 and 5!!! are'held in their operated position. The reopening of the communication circuit by the operation of relay 522 causes the armature of relay 5|2 to open the operating circuit for relays 531 and 550. Relays 531 and 550 release and thereby cause the subsequent release of relays 5|1 and 5|9 which in turn cause the subsequent release of relay 522 which again closes the line. By this sequence of operations the line has been opened for a period equal to the sum of the release time of relays 5|2, 550, 531, 5|9, and 522 plus the operate time of relay 545. Upon the closure of the line the whole chain of relays will reoperate and the action will be repeated. Subsequent breaks, however, will not include the operate time of relay 546. At each release of relay 531 the wipers 5|5 and 5|6 are advanced one step. This sequence of operations continues until the selector reaches the fth segment, or terminal, on bank No. 2 to which the winding of relay 530 is connected. While the wiper 5| 5 is on the iifth terminal, relays 5|9 and 5|1 release and apply the ground at the upper contact of off-normal spring 5|8, to the make-bcfore-break contact of relay 5|9, back contact and upper armature of relay 5|1, outer lower' armature and front contact of relay 522, conductor 523, make-before-break contact of relay 524, Wiper 5| 6 on its associated fth terminal through the winding of relay 530 to grounded battery. Relay 530 operates and locks over its upper armature and contact, conductor 532, confor relays 525 and 541. When relay 522 releases after the release oi relays 5|1 and 5I9, it closes the communication circuit and opens the other side of a parallel holding circuit for relays 524 and 513i thereby releasing relays 524 and 541. Relay 551 in releasing opens the operating circuit for relays 553 and 546 and the holding circuit for relay 535. Relays 558, 545, and 53B release. Relay 522 in releasing also prepares a circuit over its outer lower armature and back y contact, which is completed by the release of relay 545 to operate release magnet 529 which operates to thereby restore the selector switch to normal. Relay 545 in releasing, short-circuits the upper armature and contact of relay 522 which had served to interrupt the communication circuit and then transfers the windings of relays 5H and 5|9, through the right-hand contact of relay 5I2. The entire selecting circuit is now normal and ready for the next call.

The operation of the equipment associated with selector switch S1, shown in Fig. 4, is identical with that shown in Fig. 5 and may be readily traced by following the description just given for the selector arrangement shown in Fig. 5. To facilitate the comparison of operation for the release of selector switch equipment shown in Fig. 4 with that shown in Fig. 5, the reference characters used in Fig. 4 correspond with those used in Fig. 5 except that the hundreds digit corresponds to the number of the figure.

Call originating at a teletypewriter subscribers station connected to the teZet'ypewrz'ter exchange amd` terminating at a teletypewriter subscribers station connected to the telephone central oyjice A call originating, say at station (H5, is initiated in any well known manner and the tele- `typewriter exchange operator, in response to line lamp 524 which is lighted by the initiation of the call, operates typing key 605 and challenges the subscriber at station SI5 in the usual manner. The subscriber'then transmits to the operators printer set the code number of the desired teletypewriter subscribers station connected to the telephone central oce. Assuming that the requested call is to teletypewriter subscribers station Sill, the teletypewriter exchange operator upon observing the recordation of the called number, say code number 530 for subscribers station 30|, inserts plug SI2 into jack 512. The teletypewriter exchange operator then operates dial 539 in the same manner as the operator at the telephone oflice operated dial M9 in estab- `lishing a call to the teletypewriter exchange as hereinbefore describd. rlShe selector circuit shown in Figs. 5 and 4 operates as hereinbefore described in response to three sets of impulses, namely 5-3-10. After the -last set of impulses (l) is dialed, relays M2, M1, 424, and M34 in Fig. 4, and relays l2, 5H, 524i, and 5M in Fig. 5 remain operated and the communication circuit is connected through the teletypewriter exchange and the telephone central oice to the subscribers station 35| 'and communication may begin. Busy lamps 442 and 542 are lighted to indicate that channel All is busy. After the completion of themessage the disconnect signal ,is transmitted by the subscriber at station @l5 and lamp 520 is thereby lighted. The teletypewriter exchange operator then operates stop key 5ft! to effect the release oi the selector switch equipment shown in Figs. 4 and 5. The release of busy relay 504 opens `the operating circuit for busy lamps 550, 551, and 552. The operator at the teletypewriter exchange may at this point remove answering plug 65| from jack 512 and call plug GEZ from jack GIS and the system is now normal and ready for the next call.

What is claimed is:

` l.. in. a communication system, a plurality ci subscribers stations, a telephone switchboard, a telegraph switchboard, line circuits respectively connecting said subscribers stations to said telephone switchboard, one or more channels interconnecting said telephone and said 'telegraph switchboard, means at each ci said subscribers stations or originating a call, a signal located at said telephone switchboard and responsive to the operation oi said means, an impulse device lccated at said telephone switchboard for transmitting over said channel to said telegraph switchboard groups or `impulses corresponding to the number oi the subscribers station originating a call, a signal at said telegraph switchboard responsive to one oi said groups of impulses, a message transmitting and receiving device at said telegraph switchboard, and manually operated means for connecting said transmitting yand receiving device to an associated channel when said signal at said telegraph switchboard is operated.

2. In a communication system, a plurality of subscribers stations, a telephone switchboard, a telegraph switchboard, line circuits respectively connecting said subscribers stations to said telephone switchboard, one or more channels interconnecting said telephone and said telegraph switchboard, means at each of said subscribers stations for originating a call, a signal located at said telephone switchboard and responsive to the operation of said means, an impulse device located at said telephone switchboard for transmitting over an associated channel to said telegraph switchboard, groups of impulses corresponding in number to the code number oi the subscribers station originating a call, a second signal at said telephone switchboard responsive to the first of said groups, a signal at said telegraph switchboard responsive to the second of said groups, circuit means responsive to the second of said groups for restoring the rst-mentioned signal to normal, other circuit means for interconnecting in response to the third of said groups an associated channel and said originating subscribers station line circuit.

. In a printing telegraph switching system, a plurality of subscribers stations, a telephone central office, a manually operated switchboard at said central omce, a plurality of line circuits respectively connecting said subscribers stations to said central oflice, line signals located at said switchboard and respectively associated with said line circuits, a current impulse device at said switchboard and a source of current therefor, for transmitting 4groups of impulses corresponding in number to the code number of any one of said subscribers stations, a teletypewriter exchange, one or more channel circuits interconnecting said central office and said exchange, a selector circuit at said central office and at said exchange simultaneously responsive to said groups of impulses transmitted by said transmitting device, a manually operated switchboard at said exchange, connecting devices at the Second mentioned switchboard and respectively associated with said subscribers line circuits for terminating said channel circuit or circuits in accordance with the code number of the calling subscribers station, line signals located at the second mentioned switchboard and respectively associated with said connecting devices, means responsive 5 to the operation of Athe selector circuit at said exchange for operating at Ysaid exchange the line signal corresponding to the calling subscribers ,station connected to said telephone central ofiice, a plurality of other subscribers 10 stations, a plurality of other line circuits ref spectively connected to said other subscribers stations, other connecting devices at the second mentioned switchboard for respectively terminating said other line circuits, link circuits at the 15 second mentioned switchboard for interconnecting any one of said connecting devices respectively associated with the rst mentioned line circuits and the connecting devices respectively associated with the second mentioned line cir- 20 cuits, a transmitting and a receiving device common yto said link circuits, switching means at each of said link circuits for connecting said transmitting and receiving device for communication purposes to any one or more of said connecting devices engaged by one of said link circuits.

4. In a printing telegraph switching system, according to claim 3, wherein each of said subscribers stations comprises switching means for transmitting a disconnect signal, each of said link circuits comprises a disconnect lamp responsive to said disconnect signal switching means, said transmitting and receiving device common to said plurality of cord circuits comprises means for transmitting to each of two interconnected subscribers stations a signal for disabling said interconnected subscribers stations, and each of said selector circuits comprises a stop key, when operated, for restoring said selector circuits in operated positions at said central office and said exchange to normal.

CLARENCE V. COLLINS. 

